Hours after Collins disclosed his sexuality in an online article, Obama reached out by phone, expressing his support and telling Collins he was impressed by his courage, the White House said.

Collins, 34, becomes the first active player in one of four major U.S. professional sports leagues to come out as gay. He has played for six teams in 12 seasons, including this past season with the Washington Wizards, and is now a free agent.

Collins' declaration in a first-person account posted on Sports Illustrated's website garnered particular attention from Democrats, many of whom have recently announced their support for gay marriage despite opposing it in the past. Obama announced his support last year during his re-election campaign.

Organizing for Action, a grassroots group run by Obama loyalists that grew out of his 2012 re-election campaign, offered its support for Collins as well, writing to Collins on Twitter on Monday that the group's supporters "stand with you today."

And first lady Michelle Obama chimed in on Twitter on Monday afternoon to applaud Collins.

"So proud of you, Jason Collins! This is a huge step forward for our country. We've got your back!" the tweet read. It was signed "mo" — signifying that the first lady personally wrote the message.

Former President Bill Clinton also voiced encouragement, releasing a statement that asks fans, NBA colleagues and the media to support and respect him. Clinton said he has known Collins since he attended Stanford University with his daughter Chelsea.

Clinton said Collins' announcement Monday is an "important moment" for professional sports and the history of the lesbian, gay, bisexual and transgender community.

Collins is "a good man who wants no more than what so many of us seek — to be able to be who we are, to do our work, to build families and to contribute to our communities," Clinton said. "For so many members of the LGBT community, these simple goals remain elusive."

Chelsea Clinton also tweeted her support for Collins Monday, saying she was proud of her friend for having the strength and courage to be the first openly gay player in the NBA..

Earlier Monday, White House spokesman Jay Carney said Collins' decision was another example of progress and evolution in the U.S. as Americans grow more accepting of gay rights and same-sex marriage. He said he hoped the 34-year-old center's NBA colleagues will also offer support.

"We view that as another example of the progress that has been made and the evolution that has been taking place in this country," Carney said.

Chad Griffin, the president of Human Rights Campaign, a gay rights group, said Collins has "forever changed the face of sports."

"No longer will prejudice and fear force gay athletes to remain silent about a fundamental part of their lives," Griffin said.

The NBA player also received support from Rep. Joe Kennedy III, D-Mass., his college roommate. Kennedy tweeted Monday that "I've always been proud to call (Collins) a friend, and I'm even prouder to stand with him today."

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